Computer users are placing a growing demand on their computers' storage capabilities. As operating systems and programs increase in complexity, power and size, as users store greater amounts of information, and as that information becomes more complex, space on the computer's hard disk drive is quickly used up. In order to gain more storage capacity, many users desire to add a second storage apparatus, such as a hard disk drive, CD drives or DVD drives, to their system.
The present invention satisfies this above need by adding a selective circuit apparatus. FIG. 1 shows a block diagram of the device bay system according to the present invention. In FIG. 1, two bay devices 22 and 24 by connected by an IDE bus 20. The IDE bus 20 is thus a means of communication between the two bay devices 22 and 24. The two bay devices 22 and 24, first bay device and second bay device, are respectively connected with the first-bay connector 32 and the second-bay connector 30. The IDE bus 20 is comprised of a standard collection of signals for communicating data, commands and status. One of these signals includes the Pass Diagnostics signal (PDIAG*) transmitted by the interface line 26.
Device Bay, which is receiving broad industry acceptance, defines an industry specification for interchangeable peripheral devices, such as hard disk drives, modems, network adapters, CD drives, DVD drives and a variety of other electronics devices. Any peripheral can be plugged into the Device Bay without users having to open the PC box or switch it off. It will allow devices to be daisy-chained and software will take care of which interface is used by the device. With Device Bay, a user would be able to insert a peripheral like a DVD drive directly into a PC without opening, rebooting or turning off the PC.
One of the most popular ways to connect a second storage apparatus to a personal computer system is on the IDE bus. IDE (Integrated Drive Electronics) is a standard electronic interface used between a computer motherboard's data paths or bus and the computer's storage devices. The IDE interface is based on the IBM PC Industry Standard Architecture (ISA) 16-bit bus standard, but it is also used in computers that use other bus standards. The IDE interface was originally designed as a hard disk drive interface that could handle only two physical drives. One or two IDE drive units may be present on each IDE controller. When two drives are installed, they are cascaded on a common data/control cable, with one assigned as the master, and the other as the slave drive. Either of the two installed drives can be configured as the master or the slave drive via the setting of one or more switches, or more commonly Berg jumpers, on the electronic printed circuit board of the drives.
To use one drive as a master drive or a first drive and the other drive as a slave drive, or a second drive, control signals indicating a master and a slave must be supplied to IDE controllers for these drives. When a controller detects the control signal indicating a master, that drive operates as a master drive. On the other hand, when a controller detects the control signal indicating a slave, then that drive operates as a slave drive.
However, the configuration of the master and slave drives in the primary and secondary cascades of a conventional IDE interface can be adjusted only by physically changing a drive jumper setting and the cabling. In other words, if the first device bay is fixed for the master drive and the second device bay for the slave drive, such assignment requires that the floppy disk or other devices not supporting the IDE interface have to plug into the second device bay. Such requirement limits the hardware configuration being easily upgrade because the specific device needs to be plugged into the specific device bay. There is therefore a great need for a computer system that may automatically assign the master/slave status of devices in the first device bay and the second device bay of a computer. The user is then freed from worrying about where is the master device between the first and second bays and the computer system is consequently easier to upgrade and use.